Wednesday, June 22, 2011

The Creative Advantage

One thing I hardly ever do is discuss what most people would consider real "Evolutionary Psychiatry."  That is,  how do diseases such as schizophrenia or autism, which in their worst forms are obviously so detrimental to evolutionary fitness that they would seem to represent a genetic dead end, continue in the gene pool.  It doesn't make much sense at first glance.  However, one could postulate that, just as the heterozygote carriers of sickle cell anemia are relatively protected against malaria, having some schizophrenia-risk genes could convey some sort of benefit for close relatives.  And one must also consider the possibility that the schizophrenia phenotype is worse now than it may have been for much of human history - with plenty of vitamin D, no wheat (speculatively :-) ) or common modern pathogens, it is possible the schizophrenia may not have developed as fully or been as debilitating.

Given dopamine's role in creativity, motivation, and drive, the suspected genetic advantage of being a relative of a schizophrenic is that you may have a bit of extra dopamine, but not so much it will make you psychotic.  Psychotic thought is disjointed and disorganized - creative thought is taking seemingly unrelated or unexpected ideas and bringing them together in a novel way.

Sounds reasonable.  But what about the data proving it?  Well, there has been a lot of speculation looking back at known geniuses and their psychopathologies.  It is felt it is no coincidence that many geniuses were not particularly psychologically healthy.  A more recent study selected 30 creative writers at a workshop and compared them to controls - writers had higher rates of affective disorders (several variations of this study have been done with the same results).  Studies of bipolar individuals showed they scored higher on scales measuring creativity than folks with unipolar depression or non-creative controls - the bipolar folks scored the same as creative healthy controls.

In Iceland, the histories of 486 male relatives of schizophrenics were investigated - these men were more likely to be prominent historically than the general population, and there was a significant increase in those who were specifically successful in creative endeavors.

But all those studies are small, and many rely on historical records.  However, a brand new paper from the British Journal of Psychiatry documents a large, population based study of 300,000 individuals with severe forms of affective disorders or schizophrenia from a large population registry in Sweden, where there is data on hospital admissions, diagnoses, IQ, occupation, and detailed family records as well.  The were able to find several tens of thousands of folks with bipolar disorder and schizophrenia, and over two hundred thousand diagnosed with unipolar depression.

The results?  People with schizophrenia and bipolar disorder (with the effect stronger in schizophrenia) were more likely to have parents and siblings who were in creative professions.  Bipolar patients also were more likely to have creative offspring.  The ORs aren't huge - ranging from around 1.2 to 1.6, but the bars don't cross the 1.0 line suggesting a real correlation.  There were no strong statistically significant correlations between having a relative with unipolar depression and engaging in creative professions (described as "including scientific and artistic occupations.")  As one would expect for a genetic link, as relationships got further away (half-siblings, cousins, etc.) the correlations weakened accordingly.

The reverse sort of "non-creative" correlation was also true - folks with schizophrenia were significantly less likely to have relatives who were accountants and auditors.

And the IQ connection (only measured in men in this Swedish registry) - those in creative professions had a higher IQ on average, however, the IQs of people with schizophrenia, unipolar depression, bipolar depression and their relatives were lower on average than people without any of the three diagnoses.  IQ was accounted for in the correlations we talked about in the previous paragraphs and did not weaken the genetic association between creativity and severe psychiatric illness (specifically bipolar disorder and schizophrenia).

Well.  That is all very interesting!  I might go on to be a real Evolutionary Psychiatrist after all.

8 comments:

  1. What if Emily your premise was formulated with a different thought? Maybe it has nothing to do with genetics and has everything to do with acquiring it after most of your brain is formed? But then something slowly diminishes the circuits and the plasticity of the system. It continues to happen until it overwhelms the system. Most with severe schizophrenia often can not find a mate. So using what we know about epigenetics and Darwinian natural selection it stands to reason that evolution should eliminate this trait. Is it really biologically plausible when you think about it in this light? Yet as you point out the incidence and prevalence are rising the last 125 years. Maybe just maybe it has nothing to do with genetics and has a lot to do with epigenetics of our environment? Dr. K

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  2. Very interesting! My ex (and father of my kids) is the child of a schizophrenic father. I suspect his birth mother also has some kind of mental illness or instability. He was adopted and only in his 20s was he acquainted with his birth parents.

    The interesting thing, to me, is that although he was raised by adoptive parents who don't have a single creative bone between the two of them, he was passionate about music and became an avid musician in his early teens. It turns out both his biological parents were musicians.

    I also suspect that my ex did not go unaffected by his genetics and seems to me to be prone to depression or some kind of mental issues.

    Anyway, both our kids also seem creative and are natural musical talents. I'm hoping they inherited the creative part, and not the illness, anyway. Time will tell...

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  3. I like that hypothesis very much, I hope it is true (I would make a terrible researcher, I think). Talk about taking one for the genes, yikes.

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  4. An interesting post. There is a lot of speculation (and it is just that) at the moment about autism and its 'association' with parental systemiser cognitive styles over empathising. That is, the more technical career patterns like those of engineering and IT and maths and statistics potentially being allied to the 'spirit' of some of the traits seen in autism (attention to detail, obsessions with systems, etc). I don't know how systemising or empathising might tie into creativity (is creativity art or science) but it strikes me that there might be some interesting parallels (or divergences) between various conditions.

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  5. http://www.nature.com/news/2011/110622/full/474429a.html in the latest Nature. Says mental disorders get worse in big cities. Check that graph from a study from 2002. The risk of schizophrenia is twice as high in big cities.
    That might be the reason why the underlying genes for these traits have not been selected against historically -- the negative phenotype is only brought forward because the environment has changed!

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  6. Yes, I've seen reports that urban kids are up to 4 times as likely to develop schizophrenia - environment is definitely a big, big factor.

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  7. "Psychotic thought is disjointed and disorganized - creative thought is taking seemingly unrelated or unexpected ideas and bringing them together in a novel way." I might have to steal this line for a chapter I'm currently writing to contribute to an edited volume on the Neuroscience of Creativity!

    I think the point about genes needed the proper environmental conditions to express or fail to express themselves is one of the biggest overlooked ideas in modern medicine. I make the analogy in my classes to the following thought experiment. Imagine a group of individuals made up of children and adults who's weights vary from very light (a 35 lb 4-year-old) to very heavy (a 275 lb, 6'2 man). As the group walks together over a cement pavement, not one of them has any risk of falling through the pavement. As soon as they step onto a frozen lake, it is the heaviest individuals who have the greatest risk of falling through the ice. This analogy applies directly to the situation of the genetic variation present in a population and individual risk (due to gene variants) to disease susceptibility. In our ancestral environment (plenty of sunshine, activity and natural movement patterns, typically proper nutrition, occasional periods of fasting, good sleep, & etc.), even those individuals with the "riskiest" gene variants (e.g., cancer, dementia, psychopathology, autoimmune disease, CVD, etc.) are highly unlikely (though not impossible) to manifest these diseases. As soon as we adopted agriculture, and especially when we adopted an industrialized diet, we stepped off the pavement and onto thinning ice. The more industrially processed our diet becomes, the thinner the ice, and the higher the rates of expression of the risky variants in the population. I think this analogy carries a lot of weight in explaining why diseases can change in their rates of expression so rapidly and dramatically in only a few generations. More importantly, it holds the key on how to turn back the expression away from modern rates and to ancestral rates. That's what the paleo movement is in general, and is the major goal of the Ancestral Health Society!

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  8. Fascinating and we had a similar discussion along these lines over at Art De Vany's forum.

    In my search to understand my recovery from bipolar (after becoming Paleo) I learned a lot about dopamine and the fact that it is thought humans became so dominant (and large brained) due to their ability to handle large(r) amounts of meat and fish which necessitated a bigger ability to process/tolerate dopamine.

    So, whizz forward several hundred thousand years and those with high function (high dopamine) creative etc individuals had a genetic advantage it has only been during the last few hundred years that these genotypes have been subjected to a diet that is far more insulinogenic and the knock on affect is the disruption to the dopamine pathways (via insulin/IGF1) causing many more occurrences of pathological presentation of what had been a group of individuals whose higher dopamine levels had until then conveyed an advantage.

    n=1 I've inherited my paternal Grandmother's bipolar aspects - she was an incredibly talented musician, my brother likewise, I probably could have been had the bipolar disruption not diverted my attention and my own daughter is probably the most talented musician of all of us!

    Now I'm 'recovered' as far as I can tell - no episodes for over a year even under duress - I'm enjoying learning to play the piano again with a much calmer persona and 'normal' focus.

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